fallback: legalize: G_INTRINSIC <2 x s16>

Snippet:

@G = external global i1

define <2 x i16> @test_pmerge_mvmn_u16x2(<2 x i16> %rs2, <2 x i16> %rs1, <2 x i16> %rd) {
  %LGV = load i1, ptr @G, align 1
  %res = call <2 x i16> @llvm.riscv.pmerge.v2i16(<2 x i16> %rs1, <2 x i16> %rs2, <2 x i16> %rd)
  %B = shl i1 true, %LGV
  store i1 %B, ptr poison, align 1
  ret <2 x i16> %res
}

; Function Attrs: nocallback nofree nosync nounwind speculatable willreturn memory(none)
declare <2 x i16> @llvm.riscv.pmerge.v2i16(<2 x i16>, <2 x i16>, <2 x i16>) #0

attributes #0 = { nocallback nofree nosync nounwind speculatable willreturn memory(none) }

Reproduce:

llc -mtriple=riscv32 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs -global-isel -global-isel-abort=2 -pass-remarks-missed=gisel.* snippet.ll -o -
llc -mtriple=riscv32 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs -global-isel=0 snippet.ll -o -

Local llc output:

remark: <unknown>:0:0: unable to legalize instruction: %5:_(<2 x s16>) = G_INTRINSIC intrinsic(@llvm.riscv.pmerge), %1:_(<2 x s16>), %0:_(<2 x s16>), %2:_(<2 x s16>) (in function: test_pmerge_mvmn_u16x2)
warning: Instruction selection used fallback path for test_pmerge_mvmn_u16x2

Occurrences (2):

Generated 2026-10-15 08:05 UTC.